draft-ietf-ecrit-requirements-03.txt   draft-ietf-ecrit-requirements-04.txt 
ECRIT H. Schulzrinne ECRIT H. Schulzrinne
Internet-Draft Columbia U. Internet-Draft Columbia U.
Expires: August 6, 2006 R. Marshall, Ed. Expires: August 23, 2006 R. Marshall, Ed.
TCS TCS
February 2, 2006 February 19, 2006
Requirements for Emergency Context Resolution with Internet Technologies Requirements for Emergency Context Resolution with Internet
draft-ietf-ecrit-requirements-03.txt Technologies
draft-ietf-ecrit-requirements-04.txt
Status of this Memo Status of this Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on August 6, 2006. This Internet-Draft will expire on August 23, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
This document enumerates requirements for emergency calls placed by This document enumerates requirements for emergency calls placed by
the public using voice-over-IP (VoIP) and general Internet multimedia the public using voice-over-IP (VoIP) and general Internet multimedia
systems, where Internet protocols are used end-to-end. systems, where Internet protocols are used end-to-end.
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or may not provide the physical-layer and layer-2 connectivity, or may not provide the physical-layer and layer-2 connectivity,
such as fiber or Ethernet. such as fiber or Ethernet.
Location: A geographic identification assigned to a region or feature Location: A geographic identification assigned to a region or feature
based on a specific coordinate system, or by other precise based on a specific coordinate system, or by other precise
information such as a street number and name. In the geocoding information such as a street number and name. In the geocoding
process, the location is defined with an x,y coordinate value process, the location is defined with an x,y coordinate value
according to the distance north or south of the equator and east according to the distance north or south of the equator and east
or west of the prime meridian. or west of the prime meridian.
Location Context Mapping System (LCMS): A system defined as a set of
mechanisms and services working together to perform a mapping,
(or, direct association), between a location and a PSAP uri
designated as responsibleto to serve that location.
Location-dependent emergency identifier: Location-dependent emergency Location-dependent emergency identifier: Location-dependent emergency
identifiers, also referred to as "emergency dial-strings" within identifiers, also referred to as "emergency dial-strings" within
this document, should be thought of as the digit sequence that is this document, should be thought of as the digit sequence that is
dialed in order to reach emergency services. There are two dial- dialed in order to reach emergency services. There are two dial-
strings, namely either a "home emergency dial-string", or a strings, namely either a "home emergency dial-string", or a
"visited emergency dial-string", and is something separate from a "visited emergency dial-string", and is something separate from a
universal emergency identifier, since each represents specific universal emergency identifier, since each represents specific
emergency identifiers which are recognized within a local emergency identifiers which are recognized within a local
geographic area or jurisdiction. geographic area or jurisdiction.
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authority. (This terminology is used by both ETSI, in ETSI SR 002 authority. (This terminology is used by both ETSI, in ETSI SR 002
180, and NENA.) In the United Kingdom, PSAPs are called Operator 180, and NENA.) In the United Kingdom, PSAPs are called Operator
Assistance Centres, in New Zealand, Communications Centres. Assistance Centres, in New Zealand, Communications Centres.
Within this document, it is assumed, unless stated otherwise, that Within this document, it is assumed, unless stated otherwise, that
PSAP is that which supports the receipt of emergency calls over PSAP is that which supports the receipt of emergency calls over
IP. It is also assumed that the PSAP is reachable by IP-based IP. It is also assumed that the PSAP is reachable by IP-based
protocols, such as SIP for call signaling and RTP for media. protocols, such as SIP for call signaling and RTP for media.
PSAP URI: PSAP URI is a general term, used to refer to the output of PSAP URI: PSAP URI is a general term, used to refer to the output of
the mapping protocol, and represents either the actual PSAP IP the mapping protocol, and represents either the actual PSAP IP
address, or some other intermediary's IP address, which points to address, or the IP address of some other intermediary, e.g. an
the actual PSAP. ESRP, which points to the actual PSAP.
Universal identifier: An emergency identifier which is recognized by Universal identifier: An emergency identifier which is recognized by
any compatible endpoint, from any geographic location as useful any compatible endpoint, from any geographic location as useful
for initiating an emergency request. A general approach to using for initiating an emergency request. A general approach to using
universal identifiers is outlined in the service URN draft universal identifiers is outlined in the service URN draft
(I-D.schulzrinne-sipping-service [5]). (I-D.schulzrinne-sipping-service [5]).
Visited emergency dial-string: A visited emergency dial-string (ref. Visited emergency dial-string: A visited emergency dial-string (ref.
Location-dependent emergency identifier) represents a sequence of Location-dependent emergency identifier) represents a sequence of
digits that is used to initiate an emergency call within a digits that is used to initiate an emergency call within a
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o (8) Location Information is used by emergency call routing entities o (8) Location Information is used by emergency call routing entities
to determine appropriate PSAP mapping. to determine appropriate PSAP mapping.
4. High-Level Requirements 4. High-Level Requirements
Below, we summarize high-level architectural requirements that guide Below, we summarize high-level architectural requirements that guide
some of the component requirements detailed later in the document. some of the component requirements detailed later in the document.
Re1. Application Service Provider: The existence of an Application Re1. Application Service Provider: The existence of an Application
Service Provider (ASP) MUST NOT be assumed. Service Provider (ASP) SHOULD NOT be assumed.
Motivation: The caller may not have an application/voice service Motivation: The caller may not have an application/voice service
provider. For example, a residence may have its own DNS domain provider. For example, a residence may have its own DNS domain
and run its own SIP proxy server for that domain. On a larger and run its own SIP proxy server for that domain. On a larger
scale, a university might provide voice services to its students scale, a university might provide voice services to its students
and staff, but not be a telecommunication provider. and staff, but not be a telecommunication provider.
Re2. International: The protocols and protocol extensions developed Re2. International: Regional, political and organizational aspects
MUST support regional, political and organizational differences. MUST be considered during the design of protocols and protocol
extensions.
Motivation: It must be possible for a device or software developed Motivation: It must be possible for a device or software developed
or purchased in one country to place emergency calls in another or purchased in one country to place emergency calls in another
country. System components should not be biased towards a country. System components should not be biased towards a
particular set of emergency numbers or languages. Also, different particular set of emergency numbers or languages. Also, different
countries have evolved different ways of organizing emergency countries have evolved different ways of organizing emergency
services, e.g. either centralizing them or having smaller regional services, e.g. either centralizing them or having smaller regional
subdivisions such as United States counties or municipalities subdivisions such as United States counties or municipalities
handle emergency calls. handle emergency calls.
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MUST NOT depend on a sole central administration authority. MUST NOT depend on a sole central administration authority.
Motivation: Once common standards are established, it must be Motivation: Once common standards are established, it must be
possible to deploy and administer emergency calling features on a possible to deploy and administer emergency calling features on a
regional or national basis without requiring coordination with regional or national basis without requiring coordination with
other regions or nations. The system cannot assume, for example, other regions or nations. The system cannot assume, for example,
that there is a single global entity issuing certificates for that there is a single global entity issuing certificates for
PSAPs, ASPs, IAPs or other participants. PSAPs, ASPs, IAPs or other participants.
Re4. Multiple Modes: Multiple communication modes, such as audio, Re4. Multiple Modes: Multiple communication modes, such as audio,
video and text messaging MUST be supported. video and text messaging MUST be supported (i.e. implemented in
the protocol, though not necessarily used).
Motivation: In PSTN, voice and text telephony (often called TTY or Motivation: In PSTN, voice and text telephony (often called TTY or
textphone in North America) are the only commonly supported media. textphone in North America) are the only commonly supported media.
Emergency calling must support a variety of media. Such media Emergency calling must support a variety of media. Such media
should include voice, conversational text (RFC 4103 [9]), instant should include voice, conversational text (RFC 4103 [9]), instant
messaging and video. messaging and video.
Re5. Alternate Mapping Sources: The mapping protocol SHOULD allow Re5. Alternate Mapping Sources: The mapping protocol SHOULD
for alternative redundant sources of mapping information, possibly implement a mechanism that allows for the retrieval of mapping
of different degrees of currency. information, possibly of different degrees of currency.
Motivation: This provides the possibility of having available Motivation: This provides the possibility of having available
alternative sources of mapping information when the normal source alternative sources of mapping information when the normal source
is unavailable or unreachable, without specifying the means by is unavailable or unreachable, without specifying the means by
which the alternative source is created or updated. which the alternative source is created or updated.
Re6. Incremental Deployment: The ECRIT mapping protocol MUST return Re6. Incremental Deployment: The ECRIT mapping protocol MUST return
URIs that are usable by a standard signaling protocol (i.e., URIs that are usable by a standard signaling protocol (i.e.,
without special emergency extensions) unless an error is returned. without special emergency extensions) unless an error is returned.
Motivation: The format of the output returned by the mapping Motivation: The format of the output returned by the mapping
protocol is in a standard format for communication protocol. For protocol is in a standard format for communication protocol. For
example, it should return something SIP specific (e.g. URI), that example, it should return something SIP specific (e.g. URI), that
any SIP capable phone would be able to use if used in a SIP any SIP capable phone would be able to use if used in a SIP
context. Special purpose URIs would not be understood by "legacy" context. Special purpose URIs would not be understood by "legacy"
SIP devices since they do not have knowledge about the mapping SIP devices since they do not have knowledge about the mapping
protocol, and therefore are not to be used. protocol, and therefore are not to be used.
Re7. Ubiquitous Triggering: It MUST be possible to invoke the Re7. Ubiquitous Triggering: The mapping protocol MUST implement,
mapping protocol at any time, from any location, by any client (not necessarily use), the ability to be invoked at any time, from
which supports the mapping protocol. any location, by any client which supports the mapping protocol.
Motivation: While end devices are the typical initiators of Motivation: While end devices are the typical initiators of
mapping service requests, it is also expected that other mapping mapping service requests, it is also expected that other mapping
clients, such as relays, 3rd party devices, PSAPs, etc. may also clients, such as relays, 3rd party devices, PSAPs, etc. may also
trigger a mapping request. trigger a mapping request.
Re8. PSAP Identification: The mapping information MUST be available Re8. PSAP Identification: The mapping information MUST be available
without having to enroll with a service provider. without having to enroll with a service provider.
Motivation: The mapping server may well be operated by a service Motivation: The mapping server may well be operated by a service
provider, but access to the server offering the mapping must not provider, but access to the server offering the mapping must not
require use of a specific ISP or VSP. require use of a specific ISP or VSP.
Re9X. No Modification of Location Databases: The mapping protocol Re9. No Modification of Location Databases: The mapping protocol
SHOULD NOT require that data within location databases be SHOULD NOT require that data within location databases be
transformed or modified in any unusual or unreasonable way in transformed or modified in any unusual or unreasonable way in
order for the mapping protocol to use the data. order for the mapping protocol to use the data.
Motivation: Databases which contain civic addresses (used within Motivation: Databases which contain civic addresses (used within
location information servers), may be used for multiple purposes location information servers), may be used for multiple purposes
and applications, (in addition to being used for emergency service and applications, (in addition to being used for emergency service
mapping only). mapping only).
5. Identifying the Caller Location 5. Identifying the Caller Location
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Discovery Protocol (LLDP) [see IEEE8021AB]. Discovery Protocol (LLDP) [see IEEE8021AB].
UA-referenced: The caller's user agent provides a reference, via a UA-referenced: The caller's user agent provides a reference, via a
permanent or temporary identifier, to the location which is stored permanent or temporary identifier, to the location which is stored
by a location service somewhere else and then retrieved by the by a location service somewhere else and then retrieved by the
PSAP. PSAP.
Proxy-inserted: A proxy along the call path inserts the location or Proxy-inserted: A proxy along the call path inserts the location or
location reference. location reference.
Lo1. Validation of Civic Location: It MUST be possible to validate a Lo1. Validation of Civic Location: The mapping protocol MUST
civic location prior to its use in an actual emergency call. implement a method that makes it possible for a mappng server to
validate a civic location prior to that location's use in an
actual emergency call.
Motivation: Location validation provides an opportunity to help Motivation: Location validation provides an opportunity to help
assure ahead of time, whether successful mapping to the assure ahead of time, whether successful mapping to the
appropriate PSAP will likely occur when it is required. appropriate PSAP will likely occur when it is required.
Validation may also help to avoid delays during emergency call Validation may also help to avoid delays during emergency call
setup due to invalid locations. setup due to invalid locations.
Lo1X. Validation Resolution: The mapping protocol MUST support the Lo2. Validation Resolution: The mapping protocol MUST support (i.e.
return of additional information which can be used to determine required to implement, though not required for use) the return of
the precision or resolution of the data elements used to determine additional information which can be used to determine the
a PSAP URI, for example. precision or resolution of the data elements used to determine a
PSAP URI, for example.
Lo1XX. Indication of non-existent location: The protocol MUST Motivation: The mapping server may not use all the data elements
support a mechanism to indicate that a location or a part of a in the provided location information to determine a match, or may
location is known to not exist, even if a valid location-to-PSAP be able to find a match based on all of the information except for
uri mapping can be provided. some specific data elements. The uniqueness of this information
set may be used to differentiate among emergency jurisdictions.
Precision or resolution in the context of this requirement might
mean, for example, explicit identification of the data elements
that were used successfully in the mapping.
Lo2. Limits to Validation: Validation of a civic location MUST NOT Lo3. Indication of non-existent location: The protocol MUST support
be required to enable any feature that is part of the emergency (i.e. must implement in the protocol, though not necessarily use)
call process. a mechanism to indicate that a location or a part of a location is
known to not exist, even if a valid location-to-PSAP uri mapping
can be provided. This mechanism includes a means to identify a
separate mechanism that could be used to resolve the discrepancy.
Motivation: The emergency authority for a given jurisdiction may
provide a means to resolve addressing problems, e.g., a URI for a
web service that can be used to report problems with an address.
The mapping response would allow this service to be identified.
Lo4. Limits to Validation: Successful validation of a civic location
MUST NOT be required to enable any feature that is part of the
emergency call process.
Motivation: In some cases, (based on a variety of factors), a Motivation: In some cases, (based on a variety of factors), a
civic location may not be considered valid. This fact should not civic location may not be considered valid. This fact should not
result in the call being dropped or rejected by any entity along result in the call being dropped or rejected by any entity along
the signaling path to the PSAP. the signaling path to the PSAP.
Lo3. Reference Datum: The mapping server MUST understand WGS-84 Lo5. Reference Datum: The mapping server MUST implement support for
coordinate reference system and may understand other reference the WGS-84 coordinate reference system and may implement support
systems. for use of other reference systems.
Lo4. Location Provided: An Emergency Services Routing Proxy (ESRP) Lo6. Location Provided: An Emergency Services Routing Proxy (ESRP)
MUST NOT remove location information after performing location MUST NOT remove location information after performing location
based routing. based routing.
Motivation: The ESRP and the PSAP use the same location Motivation: The ESRP and the PSAP use the same location
information object but for a different purpose. Therefore, the information object but for a different purpose. Therefore, the
PSAP still requires the receipt of information which represents PSAP still requires the receipt of information which represents
the end device's location. the end device's location.
Lo5. 3D Sensitive Mapping: The mapping protocol MUST accept either a Lo7. 3D Sensitive Mapping: The mapping protocol MUST implement
2D or 3D mapping request, and return an appropriate result, based support for both 2D and 3D location information, and may accept
on which type of input is used. either a 2D or 3D mapping request as input, so to return an
appropriate result, based on which type of input is used.
Motivation: It is expected that provisioning systems will accept Motivation: It is expected that provisioning systems will accept
both 2D and 3D data. When a 3D request is presented to an area both 2D and 3D data. When a 3D request is presented to an area
only defined by 2D data, the mapping result would be the same as only defined by 2D data, the mapping result would be the same as
if the height/altitude dimension was omitted on the request." if the height/altitude dimension was omitted on the request."
6. Emergency Identifier 6. Emergency Identifier
Id1. Universal Identifier Setup: One or more universal emergency Id1. Universal Identifier Setup: One or more universal emergency
identifiers MUST be recognized by any device or network element identifiers MUST be recognized by any device or network element
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recognize an emergency call throughout the call setup. This is recognize an emergency call throughout the call setup. This is
regardless of the device location, the application (voice) service regardless of the device location, the application (voice) service
provider used (if any at all), or of any other factor. Examples provider used (if any at all), or of any other factor. Examples
of these might include: 911, 112, and sos.*. of these might include: 911, 112, and sos.*.
Id2. Universal Identifier Resolution: Where multiple emergency Id2. Universal Identifier Resolution: Where multiple emergency
service types exist, it MUST be possible to treat each emergency service types exist, it MUST be possible to treat each emergency
identifier separately, based on the specific type of emergency identifier separately, based on the specific type of emergency
help requested. help requested.
Id2. Universal Identifier Resolution: Where multiple emergency
service types exist, the mapping protocol MUST support the
individual treatment of each emergency identifier used, based on
the specific type of emergency help requested.
Motivation: Some jurisdictions may have multiple types of Motivation: Some jurisdictions may have multiple types of
emergency services available at the same level, (e.g. fire, emergency services available at the same level, (e.g. fire,
police, ambulance), in which case it is important that any one police, ambulance), in which case it is important that any one
could be selected directly. could be selected directly.
Id3. Emergency Marking: Any device in the signaling path that Id3. Emergency Marking: Any device in the signaling path that
recognizes by some means that the signaling is associated with an recognizes by some means that the signaling is associated with an
emergency call MUST add the emergency indication called for in Id1 emergency call MUST add a specific emergency indication, if it
to the signaling before forwarding it. This marking mechanism doesn't already exist, to the signaling before forwarding it.
must be different than QoS marking. This marking mechanism must be different than QoS marking.
Motivation: Marking ensures proper handling as an emergency call Motivation: Marking ensures proper handling as an emergency call
by downstream elements that may not recognize, for example, a by downstream elements that may not recognize, for example, a
local variant of a logical emergency address. local variant of a logical emergency address.
Id4. Emergency Identifier-based Marking: User agents, proxies, and Id4. Emergency Identifier-based Marking: User agents, proxies, and
other network elements that process signaling associated with other network elements that process signaling associated with
emergency calls SHOULD be configured to recognize a reasonable emergency calls SHOULD be configured to recognize a reasonable
selection of logical emergency identifiers as a means to initiate selection of logical emergency identifiers as a means to initiate
emergency marking. emergency marking.
Motivation: Since user devices roam, emergency identifiers may Motivation: Since user devices roam, emergency identifiers may
vary from region to region. It is therefore important that a vary from region to region. It is therefore important that a
network entity be able to perform mapping and/or call routing network entity be able to perform mapping and/or call routing
within the context of its own point of origin rather than relying within the context of its own point of origin rather than relying
on non-local logical emergency identifiers as the only basis for on non-local logical emergency identifiers as the only basis for
emergency marking of calls. emergency marking of calls.
Id5. Prevention of Fraud: A call identified as an emergency call or Id5. Prevention of Fraud: A call MUST be routed to a PSAP if it is
marked as such in accordance with the above requirements for identified as an emergency call or is marked as such in accordance
marking MUST be routed to a PSAP. with the above emergency marking requirements.
Motivation: this prevents use of the emergency call indication to Motivation: this prevents use of the emergency call indication to
gain access to call features or authentication override for non- gain access to call features or authentication override for non-
emergency purposes. emergency purposes.
Id6. Extensibility of emergency service types: The list of emergency Id6. Extensibility of emergency service types: The list of emergency
service types MUST be extensible, and it is not necessary to service types MUST be extensible, and it is not necessary to
provide mapping for every possible service type. provide mapping for every possible service type.
Motivation: The use of a service type is locally determined. Motivation: The use of a service type is locally determined.
Id6X. Discovery of emergency dial-string: The mapping protocol MUST Id7. Discovery of emergency dial-string: The mapping protocol MUST
support a mechanism to discover existing location-dependent support (i.e. implement, though not necessarily use) a mechanism
emergency identifiers, known as emergency dial-strings, (e.g. to discover existing location-dependent emergency identifiers,
9-1-1, 1-1-2), appropriate for the location of the caller. known as emergency dial-strings, (e.g. 9-1-1, 1-1-2), appropriate
for the location of the caller.
Motivation: Users are trained to dial the appropriate emergency Motivation: Users are trained to dial the appropriate emergency
dial-string to reach emergency services. There needs to be a way dial-string to reach emergency services. There needs to be a way
to figure out what the dial-string is within the local environment to figure out what the dial-string is within the local environment
of the caller. of the caller.
Id6XX. XXX: The SIP UA SHOULD translate home emergency dial-strings Id8. Local Identifier Translation: The SIP UA SHOULD translate home
to universal emergency identifiers. The UA is most likely pre- emergency dial-strings to universal emergency identifiers. The UA
provisioned with this information to be able to make such a would most likely be pre-provisioned with the appropriate
translation. A mechanism to provide the user's home emergency information in order to make such a translation. This assumes
dial-strings MUST be available. that a mechanism to provide the user's home emergency dial-strings
be available.
Id7. Emergency Identifier Replacement: For each signaling protocol Id9. Emergency Identifier Replacement: For each signaling protocol
that can be used in an emergency call, reserved identifiers SHOULD that can be used in an emergency call, reserved identifiers SHOULD
be allowed to replace the original emergency identifier, based on be allowed to replace the original emergency identifier, based on
local conventions, regulations, or preference (e.g. as in the case local conventions, regulations, or preference (e.g. as in the case
of an enterprise). of an enterprise).
Motivation: Any signaling protocol requires the use of some Motivation: Any signaling protocol requires the use of some
identifier to indicate the called party, and the user terminal may identifier to indicate the called party, and the user terminal may
lack the capability to determine the actual emergency address lack the capability to determine the actual emergency address
(PSAP uri). The use of local conventions may be required as a (PSAP uri). The use of local conventions may be required as a
transition mechanism. Note: Such use complicates international transition mechanism. Note: Such use complicates international
movement of the user terminal, and evolution to a standardized movement of the user terminal, and evolution to a standardized
universal emergency identifier or set of identifiers is preferred. universal emergency identifier or set of identifiers is preferred.
Id8. Universal Identifier Recognition: Universal identifier(s), MUST Id10. Universal Identifier Recognition: Universal identifier(s),
be universally recognizable by any network element which supports MUST be universally recognizable (as the label suggests), by any
the ECRIT protocol." network element which supports the (ECRIT) mapping protocol.
Id9. Universal Identifier Unrecognized: A call MUST be recognized as
emergency call even if the specific emergency service requested is Id11. Universal Identifier Unrecognized: A call MUST be recognized
not recognized." as emergency call even if the specific emergency service requested
is not recognized.
"Motivation: In order to have a robust system that supports "Motivation: In order to have a robust system that supports
incremental Service deployment while still maintaining a fallback incremental service deployment while still maintaining a fallback
capability." capability."
Id10X. Translation of emergency dial-strings: The SIP UA SHOULD Id12. Translation of emergency dial-strings: The SIP UA SHOULD
translate both home and visited emergency dial-strings into a translate both home and visited emergency dial-strings into a
universal emergency identifier. universal emergency identifier.
Id11X. Detection of visited emergency dial-strings: The mapping Id13. Detection of visited emergency dial-strings: The mapping
protocol MUST support a mechanism to allow the end device to learn protocol MUST support (i.e. implement, though not necessarily
visited emergency dial-strings. use), a mechanism to allow the end device to learn visited
emergency dial-strings.
Motivation: Scenarios exist where a user dials a visited emergency Motivation: Scenarios exist where a user dials a visited emergency
dial-string that is different from the home emergency dial-string: dial-string that is different from the home emergency dial-string:
If a user of a UA visits a foreign country, observes a fire truck If a user of a UA visits a foreign country, observes a fire truck
with 999 on the side, the expectation is to be able to dial that with 999 on the side, the expectation is to be able to dial that
same number to summon a fire truck; Another use case cited is same number to summon a fire truck; Another use case cited is
where a tourist collapses, and a "good Samaritan" uses the where a tourist collapses, and a "good Samaritan" uses the
tourist's cell phone to dial a local emergency number. tourist's cell phone to dial a local emergency number.
7. Mapping Protocol 7. Mapping Protocol
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for this particular geographic area. In particular, the location for this particular geographic area. In particular, the location
determination should not be fooled by the location of IP telephony determination should not be fooled by the location of IP telephony
gateways or dial-in lines into a corporate LAN (and dispatch gateways or dial-in lines into a corporate LAN (and dispatch
emergency help to the gateway or campus, rather than the caller), emergency help to the gateway or campus, rather than the caller),
multi-site LANs and similar arrangements. multi-site LANs and similar arrangements.
Motivation: Routing to the wrong PSAP will result in delays in Motivation: Routing to the wrong PSAP will result in delays in
handling emergencies as calls are redirected, and result in handling emergencies as calls are redirected, and result in
inefficient use of PSAP resources at the initial point of contact. inefficient use of PSAP resources at the initial point of contact.
Ma2. Mapping redirection: The mapping protocol MUST support Ma2. Mapping redirection: The mapping protocol MUST support (i.e.
redirection functionality, since in some cases, an initial mapping implement for use) redirection functionality, since in some cases,
may provide a single URL for a large geographic area. Redirection an initial mapping may provide a single URL for a large geographic
is needed to then re-invokes the mapping protocol on a different area. Redirection is needed to then re-invokes the mapping
database to obtain another URL for a more resolute ESRP or PSAP, protocol on a different database to obtain another URL for a more
which covers a smaller area. resolute ESRP or PSAP, which covers a smaller area.
Motivation: The more local the mapping output is, the more Motivation: The more local the mapping output is, the more
favorable (in most cases) the likely outcome will be for the favorable (in most cases) the likely outcome will be for the
emergency caller. emergency caller.
Ma3. Minimal additional delay: The execution of the mapping protocol Ma3. Minimal additional delay: The execution of the mapping protocol
SHOULD minimize the amount of additional delay to the overall SHOULD minimize the amount of additional delay to the overall
call-setup time. call-setup time.
Motivation: Since outbound proxies will likely be asked to resolve Motivation: Since outbound proxies will likely be asked to resolve
the same geographic coordinates repeatedly, a suitable time- the same geographic coordinates repeatedly, a suitable time-
limited caching mechanism should be supported. limited caching mechanism should be supported.
Ma4. Referral: The mapping client MUST be able to contact any server Ma4. Referral: The mapping protocol MUST support (i.e. Implement
and be referred to another server that is more qualified to answer for use), a mechanism for the mapping client to be able to contact
the query. any mapping server and be referred to another server that is more
qualified to answer the query.
Motivation: This requirement alleviates the potential for Motivation: This requirement alleviates the potential for
incorrect configurations to cause calls to fail, particularly for incorrect configurations to cause calls to fail, particularly for
caller-based queries. caller-based queries.
Ma5. Multiple Response URIs: The mapping protocol response MUST Ma5. Multiple Response URIs: The mapping protocol response MUST
allow the return of multiple URIs. support (i.e. implement, though not necessarily use), the
inclusion of multiple URIs in the response.
Motivation: In response to a mapping request, a server will Motivation: In response to a mapping request, a server will
normally provide a URI or set of URIs for contacting the normally provide a URI or set of URIs for contacting the
appropriate PSAP. appropriate PSAP.
Ma6. URI - Alternate Contact: The mapping protocol MUST be able to Ma6. URI - Alternate Contact: The mapping protocol MUST support
return a URI or contact method explicitly marked as an alternate (i.e. implement, though not necessarily use), the return of a URI
contact. or contact method explicitly marked as an alternate contact.
Motivation: In response to a mapping request, if an expected URI Motivation: In response to a mapping request, if an expected URI
is unable to be returned, then mapping server may return an is unable to be returned, then mapping server may return an
alternate URI. When and how this would be used will be described alternate URI. When and how this would be used will be described
in an operational document. in an operational document.
Ma7. Multiple PSAP URI's: The mapping protocol MUST be able to Ma7. Multiple PSAP URIs: The mapping protocol MUST be able to return
multiple URIs for different PSAPs that cover the same area.
Ma7. Multiple PSAP URIs: The mapping protocol MUST support (i.e.
implement, though not necessarily use), a method to be able to
return multiple URIs for different PSAPs that cover the same area. return multiple URIs for different PSAPs that cover the same area.
Ma8. URL properties: The mapping protocol must provide additional Ma8. URL properties: The mapping protocol must provide additional
information that allows the querying entity to determine relevant information that allows the querying entity to determine relevant
properties of the URL. properties of the URL.
Ma8. URL properties: The mapping protocol MUST support (i.e.
implement, thought not necessarily use), the ability to provide
additional information that allows the querying entity to
determine relevant properties of the URL.
Motivation: In some cases, the same geographic area is served by Motivation: In some cases, the same geographic area is served by
several PSAPs, for example, a corporate campus might be served by several PSAPs, for example, a corporate campus might be served by
both a corporate security department and the municipal PSAP. The both a corporate security department and the municipal PSAP. The
mapping protocol should then return URLs for both, with mapping protocol should then return URLs for both, with
information allowing the querying entity to choose one or the information allowing the querying entity to choose one or the
other. This determination could be made by either an ESRP, based other. This determination could be made by either an ESRP, based
on local policy, or by direct user choice, in the case of caller- on local policy, or by direct user choice, in the case of caller-
based trigger methods. based trigger methods.
Ma9. Traceable resolution: The entity requesting mapping SHOULD be Ma9. Traceable resolution: The mapping protocol SHOULD support the
able to determine the entity or entities which provided the ability of the mapping client to be able to determine the entity
emergency address resolution information. or entities which provided the emergency address resolution
information.
Motivation: To provide operational traceability in case of errors. Motivation: To provide operational traceability in case of errors.
Ma9X. URI for error reporting: The mapping protocol MUST have a Ma10. URI for error reporting: The mapping protocol MUST support
mechanism to return a urii that can be used to report a suspected (i.e. implement for use) a mechanism to return a URI that can be
or known error within the mapping database. used to report a suspected or known error within the mapping
database.
Ma10. Resilience against server failure: A client MUST be able to Ma11. Resilience against server failure: The mapping protocol MUST
fail over to another replica of the mapping server, so that a support (i.e. implement for use) a mechanism to enable the mapping
failure of a server does not endanger the ability to perform the client to be able to fail over to another replica of the mapping
mapping. server, so that a failure of a server does not endanger the
ability to perform the mapping.
Ma11. Incrementally deployable: The mapping function MUST be capable Ma12. Incrementally deployable: The mapping protocol MUST be
of being deployed incrementally. designed in such a way that supports the incremental deployment of
mapping services.
Motivation: It must not be necessary, for example, to have a Motivation: It must not be necessary, for example, to have a
global street level database before deploying the system. It is global street level database before deploying the system. It is
acceptable to have some misrouting of calls when the database does acceptable to have some misrouting of calls when the database does
not (yet) contain accurate boundary information. not (yet) contain accurate boundary information.
Ma12X. URI for error resolution: The mapping protocol MUST have a Ma13. Mapping requested from anywhere: The mapping protocol MUST
mechanism to return a reference URI which can be used to report a support (i.e. implement, though not necessarily use) the ability
suspected error in the mapping database. to provide mapping information in response to queries from any
(earthly) location, regardless of where the mapping client is
Ma13. Mapping requested from anywhere: The mapping protocol MUST be located, either geographically or by network location.
able to provide the mapping regardless of where the mapping client
is located, either geographically or by network location.
Motivation: The mapping client, (such as the ESRP), may not Motivation: The mapping client, (such as the ESRP), may not
necessarily be anywhere close to the caller or the appropriate necessarily be anywhere close to the caller or the appropriate
PSAP, but must still be able to obtain a mapping. PSAP, but must still be able to obtain a mapping.
Ma14. Location Updates: It SHOULD be possible to have updates of Ma14. Location Updates: The mapping protocol MUST support (i.e.
location. implement, though not necessarily use) the ability to provide
location updates. Mapping services should implement the
mechanisms to provide updated location.
Motivation: Updated location information may have an impact on Motivation: Updated location information may have an impact on
PSAP routing. In some cases it may be possible to redirect that PSAP routing. In some cases it may be possible to redirect that
call to a more appropriate PSAP (some device measurement call to a more appropriate PSAP (some device measurement
techniques provide quick (i.e. early), but imprecise "first fix" techniques provide quick (i.e. early), but imprecise "first fix"
location). location).
Ma15. Extensible Protocol: The mapping protocol MUST be extensible Ma15. Extensible Protocol: The mapping protocol MUST be designed to
to allow for the inclusion of new location fields. support the extensibility of location data elements, both for new
and existing fields.
Motivation: This is needed, for example, to accommodate future Motivation: This is needed, for example, to accommodate future
extensions to location information that might be included in the extensions to location information that might be included in the
PIDF-LO (RFC 4119 [3]). PIDF-LO (RFC 4119 [3]).
Ma16. Split responsibility: The mapping protocol MUST allow that Ma16. Split responsibility: The mapping protocol MUST support (i.e.
within a single level of the civic location hierarchy, multiple implement for use) the division of data subset handling between
mapping servers handle subsets of the data elements. multiple mapping servers within a single level of a civic location
hierarchy.
Motivation: For example, two directories for the same city or Motivation: For example, two directories for the same city or
county may handle different streets within that city or county. county may handle different streets within that city or county.
Ma17. Pervasive Mapping: The mapping function MUST be able to be Ma17. Pervasive Mapping: The mapping protocol MUST support (i.e.
implement for use) the ability of the mapping function to be
invoked at any time, including while an emergency call is in invoked at any time, including while an emergency call is in
process. process.
Ma18. Baseline query protocol: A mandatory-to-implement protocol Ma18. Baseline query protocol: A mandatory-to-implement protocol
MUST be specified. MUST be specified.
Motivation: An over-abundance of similarly-capable choices appears Motivation: An over-abundance of similarly-capable choices appears
undesirable for interoperability. undesirable for interoperability.
Ma19. Single URI Scheme: The mapping protocol MAY return multiple Ma19. Single URI Scheme: The mapping protocol MAY return multiple
URIs, though it SHOULD return only one URI per scheme, so that URIs, though it SHOULD return only one URI per scheme, so that
clients are not required to select among different targets for the clients are not required to select among different targets for the
same contact protocol. same contact protocol.
Motivation: There may be two or more URIs returned when multiple Motivation: There may be two or more URIs returned when multiple
contact protocols are available (e.g. SIP and SMS). The client contact protocols are available (e.g. SIP and SMS). The client
may select among multiple contact protocols based on its may select among multiple contact protocols based on its
capabilities, preference settings, or availability. capabilities, preference settings, or availability.
Ma20X. Separation of Identity from mapping: The mapping function MUST Ma20. Separation of Identity from mapping: The mapping protocol MUST
NOT require the true identity of the target for which the location NOT require the true identity of the target for which the location
information is attributed. Ideally, no identity information is information is attributed. Ideally, no identity information is
provided to the mapping function. Where identity information is provided via the mapping protocol. Where identity information is
provided, it may be in the form of an unlinked pseudonym as provided, it may be in the form of an unlinked pseudonym as
defined in RFC 3963. defined in RFC 3963.
Ma21X. Location delivery by-value: The mapping protocol MUST support Ma21. Location delivery by-value: The mapping protocol MUST support
the delivery of location information by-value and MAY support de- (i.e. implement, though not necessarily use) the delivery of
referencing of location references. Location by-reference is not location information by-value, though may alternatively support
one of the evaluation criteria. The mapping protocol is not de-referencing of specific location references.
required to support the ability to de-reference location
references.
Ma22X. Alternate community names: The mapping protocol MUST support Motivation: Location by-reference is not one of the evaluation
both the jurisdiction community name and the postal community name criteria for a mapping protocol presented here. (i.e. the mapping
fields in the PIDF-LO. protocol is not required to support the ability to de-reference
specific location references.)
Ma22. Alternate community names: The mapping protocol MUST support
(i.e. implement, though not necessarily use) both the jurisdiction
community name and the postal community name fields within the
PIDF-LO data.
Motivation: A mapping query must be accepted with either or both Motivation: A mapping query must be accepted with either or both
community name fields, and provide appropriate responses. If a community name fields, and provide appropriate responses. If a
mapping query is made with only one field present, given that the mapping query is made with only one field present, given that the
database has both fields populated, the mapping protocol response database has both fields populated, the mapping protocol response
should return both available fields. should return both available fields.
Ma23X. Support for alias locations: The mapping protocol MUST support Ma23. Support for alias locations: The mapping protocol MUST support
one or more aliases for a specific location entry. (i.e. implement, though not necessarily use) one or more aliases
for a specific location entry.
Motivation: It should be possible to relate one entry to another Motivation: It should be possible to relate one entry to another
and be able to determine which is the "primary" entry and which is and be able to determine which is the "primary" entry and which is
the alias. The result of aliasing is always that mapping from the the alias. The result of aliasing is always that mapping from the
primary or any of the aliases is the same. primary or any of the aliases is the same.
Ma24X. Pre-call mapping for fallback: The mapping protocol MUST Ma24. Pre-call mapping for fallback: The mapping protocol MUST
support LCMS queries prior to making an emergency call. support (i.e. implement, though not necessarily use) LCMS queries
prior to making an emergency call.
Motivation: Used as a fallback mechanism only, if a LCMS query Motivation: Used as a fallback mechanism only, if a LCMS query
fails at emergency call time, it may be advantageous to have prior fails at emergency call time, it may be advantageous to have prior
knowledge of the PSAP URI. This prior knowledge would be obtained knowledge of the PSAP URI. This prior knowledge would be obtained
by performing an LCMS query at any time prior to an emergency by performing an LCMS query at any time prior to an emergency
call. call.
8. Security Considerations 8. Security Considerations
Note: Security Considerations are referenced in the ECRIT security Note: Security Considerations are referenced in the ECRIT security
skipping to change at page 27, line 7 skipping to change at page 27, line 7
Brian Rosen br@brianrosen.net Brian Rosen br@brianrosen.net
Richard Stastny Richard.Stastny@oefeg.at Richard Stastny Richard.Stastny@oefeg.at
Martin Thomson Martin.Thomson@andrew.com Martin Thomson Martin.Thomson@andrew.com
James Winterbottom James.Winterbottom@andrew.com James Winterbottom James.Winterbottom@andrew.com
10. Acknowledgments 10. Acknowledgments
We would like to thank Michael Hammer, Ted Hardie, Marc Linsner, In addition to thanking those listed above, we would like to also
Andrew Newton, James Polk, Tom Taylor, and Hannes Tschofenig for thank Michael Hammer, Ted Hardie, Marc Linsner, Barbara Stark, Clive
their input. D.W. Feather, Keith Drage, Raymond Forbes, Tim Dunn, Steve Norreys,
Patti McCalmont, Rohan Mahy, Nate Wilcox, Michael Haberler, Jonathan
Rosenberg, Shida Schubert, John Schnizlein, Benny Rodrig, John
Rosenberg, Patrik Faeltstroem, Barry Dingle, Gunnar Hellstrom, James
Seng, Byron Smith, Cullen Jennings, Don Mitchell, John Morris, Jon
Peterson, Randall Gellens, Guy Caron, Andrew Newton, James Polk, Tom
Taylor, and Hannes Tschofenig for their invaluable input.
11. References 11. References
11.1. Normative References 11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host [2] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based Location Configuration Protocol Option for Coordinate-based Location
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